Count Word Pairs Java

Question

I have this programming, and for the first time in our class we are writing code in Java. I asked my instructor and could not get any help.

The program should count the word pairs from the file and display them as follows:

abc: hec, 1 

This means that there was only one time in the text file, followed by "abc" followed by "hec". I need to use Framework Collections in java. Here is what I still have.

  import java.io.File; import java.io.FileInputStream; import java.io.InputStream; import java.io.FileNotFoundException; import java.util.Scanner; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.ArrayList; // By default, this code will get its input data from the Java standard input, // java.lang.System.in. To allow input to come from a file instead, which can be // useful when debugging your code, you can provide a file name as the first // command line argument. When you do this, the input data will come from the // named file instead. If the input file is in the project directory, you will // not need to provide any path information. // // In BlueJ, specify the command line argument when you call main(). // // In Eclipse, specify the command line argument in the project "Run Configuration." public class Assignment1 { // returns an InputStream that gets data from the named file private static InputStream getFileInputStream(String fileName) { InputStream inputStream; try { inputStream = new FileInputStream(new File(fileName)); } catch (FileNotFoundException e) { // no file with this name exists System.err.println(e.getMessage()); inputStream = null; } return inputStream; } public static void main(String[] args) { // Create an input stream for reading the data. The default is // System.in (which is the keyboard). If there is an arg provided // on the command line then we'll use the file instead. InputStream in = System.in; if (args.length >= 1) { in = getFileInputStream(args[0]); } // Now that we know where the data is coming from we'll start processing. // Notice that getFileInputStream could have generated an error and left "in" // as null. We should check that here and avoid trying to process the stream // data if there was an error. if (in != null) { // Using a Scanner object to read one word at a time from the input stream. @SuppressWarnings("resource") Scanner sc = new Scanner(in); String word; System.out.printf("CS261 - Assignment 1 - Matheus Konzen Iser%n%n"); // Continue getting words until we reach the end of input List<String> inputWords = new ArrayList<String>(); Map<String, List<String>> result = new HashMap<String, List<String>>(); while (sc.hasNext()) { word = sc.next(); if (!word.equals("---")) { // do something with each word in the input // replace this line with your code (probably more than one line of code) inputWords.add(word); } for(int i = 0; i < inputWords.size() - 1; i++){ // Create references to this word and next word: String thisWord = inputWords.get(i); String nextWord = inputWords.get(i+1); // If this word is not in the result Map yet, // then add it and create a new empy list for it. if(!result.containsKey(thisWord)){ result.put(thisWord, new ArrayList<String>()); } // Add nextWord to the list of adjacent words to thisWord: result.get(thisWord).add(nextWord); } //OUTPUT for(Entry e : result.entrySet()){ System.out.println(e.getKey() + ":"); // Count the number of unique instances in the list: Map<String, Integer>count = new HashMap<String, Integer>(); List<String>words = (List)e.getValue(); for(String s : words){ if(!count.containsKey(s)){ count.put(s, 1); } else{ count.put(s, count.get(s) + 1); } } // Print the occurances of following symbols: for(Entry f : count.entrySet()){ System.out.println(" " + f.getKey() + ", " + f.getValue()); } } } System.out.printf("%nbye...%n"); } } } 

The problem I am facing right now is that it runs too often in a loop:

 if (!word.equals("---")) { // do something with each word in the input // replace this line with your code (probably more than one line of code) inputWords.add(word); } 

Does anyone have any ideas or advice on this?

Answer 1

I find this part confusing:

 while (sc.hasNext()) { word = sc.next(); if (!word.equals("---")) { // do something with each word in the input // replace this line with your code (probably more than one line of code) inputWords.add(word); } for(int i = 0; i < inputWords.size() - 1; i++){ 

I think you probably mean something more:

 // Add all words (other than "---") into inputWords while (sc.hasNext()) { word = sc.next(); if (!word.equals("---")) { inputWords.add(word); } } // Now iterate over inputWords and process each word one-by-one for (int i = 0; i < inputWords.size(); i++) { 

It looks like you are trying to read all the words in inputWords and then process them while your code iterates through the list after each word you add.

Note also that your state in the for loop is too conservative, so you will miss the last word. Removing - 1 will give you an index for each word.